Convergence of Internal Tide Energy in deep water in the Suruga Trough

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Internal wave energy originated from a steep slope region can be incident in deep water under continuous stratification. In the previous study, we found the strong tidal currents above the sea bottom in the Suruga Trough, near the Suruga Bay head, and explained such phenomena to be associated with internal tides (Matsuyama et al.1993). The observed internal tides are possible to be generated at the northern part of the Izu Ridge and propagate on the sea bottom in the Suruga Trough. This study is performed to investigate a mechanism of energy concentrtion in deep water of the trough from the upper slope region such as the Izu Ridge and the Suruga Bay head by both the current measurements and numerical experiments. The current measurements were carried out on the northern part of the Izu Ridge and the slope region of the Suruga Bay head, two times, in fall of 1996 and summer of 1997. To obtain the vertical sections of the horizontal current, the repeated observations by ship were made cross the slope region by using ADCP (Acoustic Doppler Current Profiler) and XBT with the current and temperature measurements at moored station. The ADCP measurements show that the internal tide energy is a structure of a narrow beam near the shelf edge and is incident in the deep water from the slope region. The numerical experiment with three dimensional model shows the internal tide to be effectively generated on the northern part of the Izu Ridge and to be propagated into the Suruga Trough having internal Kelvin waves. The results in this study play a important role on study on propagation of the internal tide energy in deep regions.